Under current practice, as in, for example, network routing systems of Cisco and other manufacturers, the upgrading, revising or other changing of the software managing of a router in such a network of interconnected router nodes requires taking the router down, effecting the software upgrade or other change (generally from software memory images), and then restarting, disrupting the routing traffic and interaction with neighboring router nodes. Historically, the problem of network routing reliability has often not been a large issue because of the redundancy of routing paths in the networks, and because of the tolerance of users to a half-minute to several minutes traffic re-routing after a particular router node has been taken out of service for a software upgrade, or has failed. The removal of a router node from the network triggers the reconverging along another path of router nodes. The router is brought down to the level of only configuration management while the software is upgraded or otherwise changed or varied, and then the router is restarted again and reconverges, enabling traffic along the initial router network path. If no alternative path exists, however, a portion of the network will be disconnected during the update.
In environments such as universities and the like, several minutes of disruption for email or the like is tolerable; but if audio or video data is being routed, or interactive interplay is involved, such reconfiguring time presents a deleterious disruption.
Through the novel techniques underlying the present invention, however, a much higher availability router is provided wherein software may be upgraded in the network router path without disrupting or interrupting traffic service therein, and without interruption even if no alternative routing paths are available in the network.